Purification of alkyl phenols



Patented Nov. 7, 1950 PURIFICATION OF ALKYL PHENOLS Jackson J. Ayo, Elizabeth, and Ferdinand J. Gajewski, Linden, N. J., assignors to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application December Serial No. 791,166

1 Claim. (01.202-57) This invention relates to a process of purifying alkylated phenols.

When higher alkylated phenols (1. e. phenols containing one or more alkyl substituents offour or more carbon atoms each) 'are employed as intermediates in the production of such products as resins by condensation with formaldehyde or surface active agents by condensation with alkylene oxides, the resulting product frequently-has a relatively poor color, being decidedly yellow to dark brown in color, even though the alkylated phenol employed actually may have been very light in color. As a result, the use of such alkylated phenols has been considerably retarded and the value of products produced therefrom appreciably lowered in many applications where color is important, although technically the products obtained from higher alkylated phenols may be superior to other available products.

We have now discovered that such alkylated phenols may be readily purified and the color of the phenol itself and more especially the color of products produced therefrom markedly improved by simple vacuum distillation of the colored crude alkylated phenol, provided that a small amount of an alkali is admixed with the crude phenol prior to vacuum distillation and this mixture of alkali and phenol is heated to a temperature about 80 C. higher than that to be used for vacuum distillation, and the thus-treated mixture then distilled under vacuum at a temperature approximately 80 below that which was employed in the heat-treating step.

The phenols which may be purified by the process of the present invention include alkylated phenols which themselves have relatively poor colors and also those which are themselves light in color but from which products having relatively poor colors are produced. These phenols may be represented by the general formula:

I w g \I/ x wherein R stands for an alkyl group of at least 4 carbon atoms, R stands for hydrogen or a similar alkyl group and X stands for hydrogen 2 phenols and cresols, 2,4-diamyl and dibutyl phenols and cresols, iso-octyl phenols and cresols, dodecyl phenols and cresols, pentadecyl phenols and cresols, octadecyl phenols and cresols, and similar alkyl phenols and cresols obtained by condensing with the'aid of an acid condensing catalyst such as sulfuric acid or BF; olefines such as those obtained inpetroleum refining, for instance butylene and isobutylene and dimers and trimers thereof, 6-18 carbon atom polypropylenes and the like with phenol or cresols; also the alkyl phenols obtained by the condensation of aliphatic alcohols, especially secondary and tertiary alcohols containing 4 to 13 carbon atoms such as secondary or tertiary amyl and butyl alcohols, dodecanol, octadecanol or alcohols obtained by oxidation of parafiin waxes and the alcohols obtained by the Fiseher-Tropsch process with phenol and cresols with the aid of such acid reacting condensation catalysts as HzSO-r or IBFs, so as to introduce into the phenol or cresol one or two alkyl groups containing 4 to 18 carbon atoms.

The details of the present invention can be most readily described by consideration oi a specific example of a preferred embodiment thereof.

Example coo g. of diamyl phenol were mixed in adistillation rlask with 6 g. of solid potassium hydroxide and the mixture heated at atmospheric pressure to 220f C. for 15 minutes. The mixture was then cooled to about 100 C. and a'vacuum soluble, surface active polyglycol ether of the diamyl phenol. The introduction of ethylene oxide was continued until 8 to 10 mols of ethylene oxide had been introduced for each mol of the phenol, at which time a test sample was readily soluble in water. water-soluble polyglycol ether of diamyl phenol had a reading of 2 on the Varnish Color System of the Institute of Paint and Varnish Research,

whereas a similar polyglycol ether produced from the same batch of diamyl phenol which had been vacuum-distilled but which had not been subjected to the high temperature alkali treatment prior thereto had a color reading of 9 or higher on the same scale.

The thus-obtained r acaaaoa It will be understood that the foregoing exoptimum amount of alkali can, of course. be

- ample is illustrative only of a specific embodlreadily determined by simple preliminary teat.

ment of the present invention and various We claim:

changes may be made therein. Thus, it will be In the purification of higher alkylated phenols noted that the temperature employed will, of 5 containing an alkyl substituent of at least 4 carcourse, depend on the specific phenol being puribon atoms by vacuum distillation at a predefied and on the degree of vacuum employed for termined temperature, the improvement which final distillation. The particular temperature comprises mixing said phenol prior to distillation and vacuum to be employed for any specific with about 1% by weight thereof of an alkali phenol can, of course, be readily determined and heating said mixture to atgmperatm-e about from usual reference tables in many instances or 80 C. higher than said predetermined vacuum by simp P liminary experiment. The essendistillation temperature for about minutes tial feature of the present invention, insofar as and thereafter cooling said-mixture and vacuum temperature is concerned. is the emp yme t distilling said phenol at said predetermined temduring the preliminary alkali heat-treating step ii t of a temperature approximately 80 C. higher JACKSON AYQ than the temperature to be employed during FERDINAND J GAJEwsm. vacuum distillation. Superatmospheric pressure, of course, may be employed during this REFERENCES CITED preliminary heating step if necessary' The following references are of record in the It will also be apparent that other alkali metal this alkalies may be employed in place of potassium me of pater-1t hydroxide and thus, sodium hydroxide or potas- UNITED STATES PATENTS sium or sodium carbonate may be used, if de- Number Name Date sired; It has been found that about 1% by weight 2,302,600 Cislak Nov. 1'7, 1942 of alkali is efiective for obtaining a marked'improvement in color of the products produced OTHER REFERENCES from the alkylated phenols. Too much alkali Industrial and Engineering (Ib y, should not be employed, since the phenolate of pp. 525 and 52'! (Apr. 1947). (Copy in Scientific the phenol will be formed and an excess of alkali Library)- may therefore result in some loss of phenol, The 

